1. Field of the Invention
The present invention relates to nutritional supplements. More particularly, the present invention relates to nutritional supplements providing zinc to a subject in need of treatment.
2. General Background of the Invention
Zinc, an essential nutrient, is the second most abundant trace element in the human body and the most abundant trace element in the eye. It is necessary for the activity of more than 200 enzymes and for the DNA binding capacity of over 400 nuclear regulatory elements. There is evidence that zinc may function as an antioxidant by protecting sulfhydryl groups from oxidation, competing with copper and iron to reduce the formation of hydroxyl radicals which are a result of redox cycling and by the induction of the antioxidant protein metallothionein (MT) which can scavenge damaging hydroxyls.
It has been suggested that oxidative stress and a decrease in antioxidant capacity play a role in several pathological conditions such as atherosclerosis, carcinogenesis, and macular degeneration. Age-related macular degeneration (AMD) is the number one cause of blindness in people over 60 in the United States. It is thought that it is an age-related defect in the retinal pigment epithelium (RPE) which contributes to this disease, however, the etiology is unknown and currently there is no cure. Our laboratory has previously reported that the antioxidants catalase, MT, and zinc decrease with age and signs of age-related macular degeneration in isolated human retinal pigment epithelial cells.
Zinc has been implicated in beneficial effects on certain prostate conditions and functions, immune system function, and cancer.
Cysteine is a non-essential amino acid necessary for the formation of sulfur containing compounds such as pyruvate, taurine, and glutathione, important in normal tissue metabolism protection and repair.
Synthesis of glutathione is largely regulated by cysteine availability. An increase in glutathione levels are beneficial when the body encounters toxic conditions such as peroxide formation, ionizing radiation, alkylating agents, or other reactive intermediates.
In premature infants, cysteine levels are low, thereby making them more susceptible to oxidative damage of hydroperoxides formed in the eye after hyperbaric oxygen treatments.
As demonstrated in the recent work by Uzzo et al., zinc can inhibit the development and progression of prostate cancer. Uzzo, R.G. et al., “Zinc inhibits nuclear factor-kappa B activation and sensitizes prostate cancer cells to cytotoxic agents” Clin. Cancer Res. 2002 8:3579–83.
Zinc has been demonstrated to be clinically beneficial in many dermatological conditions. For example, see the multicenter randomized study of Pierard C. Franchiment et al., “A Multicenter Randomized Trial of Ketoconazole 2% and Zinc Pyrythione 1% Shampoos in Severe Dandruff and Seborrheic Dermatitis”, Skin Pharmacol Appl Skin Physiol. 2002 15:434–41.
The following U.S. Patents, and all references mentioned herein, are incorporated herein by reference:    U.S. Pat. No. 5,844,089 Genetically fused globin-like polypeptides having hemoglobin-like activity    U.S. Pat. No. 5,844,088 Hemoglobin-like protein comprising genetically fused globin-like polypeptides    U.S. Pat. No. 5,801,019 DNA encoding fused alpha-beta globin pseuodimer and production of pseudotetrameric hemoglobin    U.S. Pat. No. 5,798,227 Co-expression of alpha and beta globins    U.S. Pat. No. 5,744,329 DNA encoding fused di-beta globins and production of pseudotetrameric hemoglobin    U.S. Pat. No. 5,739,011 DNA for the production of multimeric hemoglobins    U.S. Pat. No. 5,599,907 Production and use of multimeric hemoglobins    U.S. Pat. No. 5,545,727 DNA encoding fused di-alpha globins and production of pseudotetrameric hemoglobin    U.S. Pat. No. 5,401,770 Antipruritic agents and antipruritic compositions thereof    U.S. Pat. Nos. 3,941,818; 4,021,569; 4,764,633.
U.S. Pat. No. 5,401,770 discloses the use of a zinc-cysteine complex in an external use antipruritic agent.